Hypotheses of the etiology of intracranial meningiomas in adults and of neoplasms of various types in children and young adults are being tested using case-control studies. There are three case groups: women under age 65 with meningiomas first diagnosed from 1972 through 1975; men under age 70 with meningiomas first diagnosed from 1972 through 1977; and young people under age 25 with an intracranial tumor of any histologic type first diagnosed from 1972 through 1977. Questionnaires have been designed to obtain data on radiation exposure, medical history, family history of tumors, occupation and consumption of tobacco, alcohol, drugs and certain foods. Standard matched pair analyses will be performed on the data from the questionnaire.